diff --git a/lnrpc/signrpc/signer_server.go b/lnrpc/signrpc/signer_server.go
index 147e146f2..c1b8e96d3 100644
--- a/lnrpc/signrpc/signer_server.go
+++ b/lnrpc/signrpc/signer_server.go
@@ -310,9 +310,12 @@ func (s *Server) SignOutputRaw(ctx context.Context, in *SignReq) (*SignResp,
 
 		// If a witness script isn't passed, then we can't proceed, as
 		// in the p2wsh case, we can't properly generate the sighash.
+		// A P2WKH doesn't need a witness script. But SignOutputRaw
+		// still needs to know the PK script that was used for the
+		// output. We'll send it in the WitnessScript field, the
+		// SignOutputRaw RPC will know what to do with it when creating
+		// the sighash.
 		if len(signDesc.WitnessScript) == 0 {
-			// TODO(roasbeef): if regualr p2wkh, then at times
-			// internally we allow script to go by
 			return nil, fmt.Errorf("witness script MUST be " +
 				"specified")
 		}